Wall Street is rallying after the Labor Department came out with the delayed employment report for September that showed only 148,000 jobs were created last month.

Market professionals had been expecting growth of 180,000 jobs — a relatively upbeat figure that seems seared on Wall Street’s collective brain despite the fact that the optimism never pans out.

I predicted that September growth would be lousy. In fact the only thing that surprised me was that the growth wasn’t more miserable. I’ll explain in a minute.

The Labor Department also announced that the unemployment rate declined to 7.2 percent, which is another exercise in deceit since that figure only dropped by 0.1 percent point because more Americans gave up looking for work.

The Obama administration and the Federal Reserve argue that Americans are voluntarily leaving the workforce because they are getting old and would prefer to watch their lawns grow.

The 800,000 government workers who were on paid vacation during the Washington shutdown — euphemistically known as a “furlough” — didn’t count in yesterday’s report.

The September employment survey was taken in the middle of the month. Federal workers were told to go home and sit by their pools on Oct. 1 and were out of the office until Oct. 17, the day the government reopened.

The Labor Department tells me that these government workers will also not show up as unemployed in the October employment report, due out on Friday, Nov. 8, despite the fact that under the strictest definition they should be counted as jobless.

The Department’s Establishment Survey of companies usually has the week containing the 12th of the month as its reference point. And as long as a person is paid for at least one day of work during that reference period, he is considered employed.

The 800,000 government workers who were furloughed didn’t get paid during the October reference period. But since Congress agreed to give them back wages the Labor Department seems to have made an exception in their case.

Without those 800,000 people in the count the Nov. 8 figure would be awful and hard to compare with other months.

The September employment report had one strike against it from the start: it is one of only three months in which the government doesn’t pump up the figures with a generous guess for jobs created by newly formed companies that may not really exist.

The Labor Department actually subtracted 26,000 jobs for small companies that might have closed without the government knowing it.

In the spring, this guess, called the birth/death Model, adds hundreds of thousands of phantom jobs a month.

The game goes like this: the Labor Department does its seasonal adjustments and then adds guesses for these new-company jobs. Then over the next few months the department revises the figures to less fanfare.

Some more revisions came out yesterday. Job growth in July was cut from 162,000 to 89,000. August, however, was revised upward from 169,000 to 193,000. A third revision of the August number will come out next month.

The Labor Department also performed some razzle-dazzle by changing definitions. Workers in peoples’ homes had not been counted as employed until they became categorized in March as being part of the education and health care services industry.

That change has added to the job count each month since March. But there’s no way of knowing how much of an influence the re-categorizing has had on the headline number.

Why is Wall Street so happy that the economy is doing poorly? Because it seems to put an end, at least for a while, the idea that the Fed will have to stop printing trillions of extra dollars as part of its Quantitative Easing experiment. Wall Street has gotten rich off QE — even if you haven’t.

Like it or not, the Fed is stuck with QE. The economy is just not performing well enough to take it off the Fed’s respirator.